Temporal and Longitudinal Mercury Trends in Burbot (Lota lota) in the Russian Arctic.

Current understanding of mercury (Hg) dynamics in the Arctic is hampered by a lack of data in the Russian Arctic region, which comprises about half of the entire Arctic watershed. This study quantified temporal and longitudinal trends in total mercury (THg) concentrations in burbot (Lota lota) in eight rivers of the Russian Arctic between 1980 and 2001, encompassing an expanse of 118 degrees of longitude. Burbot THg concentrations declined by an average of 2.6% annually across all eight rivers during the study period, decreasing by 39% from 0.171 µg g-1 wet weight (w.w.) in 1980 to 0.104 µg g-1 w.w. in 2001. THg concentrations in burbot also declined by an average of 1.8% per 10° of longitude from west to east across the study area between 1988 and 2001. These results, in combination with those of previous studies, suggest that Hg trends in Arctic freshwater fishes before 2001 were spatially and temporally heterogeneous, as those in the North American Arctic were mostly increasing while those in the Russian Arctic were mostly decreasing. It is suggested that Hg trends in Arctic animals may be influenced by both depositional and postdepositional processes.

Low and declining mercury in arctic Russian rivers.

Mercury (Hg) dynamics in the Arctic is receiving increasing attention, but further understanding is limited by a lack of studies in Russia, which encompasses the majority of the pan-Arctic watershed. This study reports Hg concentrations and trends in burbot (Lota lota) from the Lena and Mezen Rivers in the Russian Arctic, and assesses the extent to which they differ from those found in burbot in arctic rivers elsewhere. Mercury concentrations in burbot in the Lena and Mezen Rivers were found to be generally lower than in 23 other locations, most of which are in the Mackenzie River Basin (Canada). Mercury concentrations in burbot in the Lena and Mezen Rivers also were found to have been declining at an annual rate of 2.3% while they have been increasing in the Mackenzie River Basin at annual rates between 2.2 and 5.1% during roughly the same time period. These contrasting patterns in Hg in burbot across the pan-Arctic may be explained by geographic heterogeneity in controlling processes, including riverine particulate material loads, historically changing atmospheric inputs, postdepositional processes, and climate change impacts.

Measurements of Cd, Cu, Pb and Zn in the lower reaches of major Eurasian arctic rivers using trace metal clean techniques.

Concentrations of dissolved and particulate Cd, Cu, Pb and Zn were determined in samples collected in summer 1998 from the lower reaches of six major Eurasian arctic rivers: the Onega, Severnaya Dvina, Mezen, Pechora, Ob and Yenisey. These data comprise some of the earliest measurements of trace metals in Eurasian arctic rivers above the estuaries using recognized clean techniques. Significant (alpha = 0.05) differences were observed among mean concentrations of particulate metals in the individual rivers (F < or = 0.006), with highest levels overall observed in the Severnaya Dvina and Yenisey. No significant differences were observed among mean concentrations of dissolved metals in the individual rivers (F = 0.10-0.84). Contributions from anthropogenic sources are suggested by comparison of trace metal ratios in the samples to crustal abundances. These results establish a baseline for assessing future responses of Eurasian arctic river systems to climate-related environmental changes and shifting patterns of pollutant discharge.

A review of riverine fluxes of hexachlorocyclohexane and DDT to the Azov and Black seas from the former USSR and Russian Federation.

While the Azov and Black seas are subject to anthropogenic pollution to a much higher extent than any other seas, this has been little studied with only a few critical reviews of contaminant fluxes to these seas. Riverine fluxes of the organochlorine pesticides (OCPs) hexachlorocyclohexane (HCH) and DDT to the Azov and Black seas from the former Soviet Union and Russian Federation were thus reviewed for 1986 to 1996. The review was based on official data and data obtained by independent specialists. The amount of HCH used, and the intensity of usage, in these river catchments decreased during the review period. Concurrently, OCP concentrations in the rivers and their fluxes also decreased according to both official and independent data. A comparison of the official and the independent data sets for 1988 revealed significant differences, reflecting the need for more rigorous sampling and analytical protocols for both data sets. According to the OGSNK/GSN data, the flux rates of the five largest rivers were ranked (from largest to smallest) as follows: Don > Dnestr > Danube > Kuban > Dnepro (alpha-HCH); Danube > Don > Dnestr > Dnepro > Kuban (gamma-HCH); Dnestr > Danube > Don > Dnepro-Kuban (DDT+DDE). For rivers with lower annual riverine discharges, the DDT fluxes were surprisingly high (0.43 to 1.49 tonnes a(-1)). According to independent data for 1988 the rankings of the rivers was: Danube > Don > Dnepro > Dnestr > Kuban (alpha-HCH); Danube > Don > Dnestr > Dnepro > Kuban (gamma-HCH); Danube > Dnepro > Dnestr > Don > Kuban (DDT); Danube > Dnepro > Don > Kuban > Dnestr (DDE). The DDT flux estimates for small rivers derived from independent data were 19 to 46 times lower than those calculated using OGSNK/GSN data. According to the independent data, the total riverine OCP transport from the Russian Federation into the Azov Sea from 1988 to 1996 was 1.288 tonnes of gamma-HCH+alpha-HCH and 1.693 tonnes of DDT+DDE while for the Black Sea they were 3.830 tonnes and 5.116 tonnes for gamma-HCH+alpha-HCH and DDT+DDE, respectively.

Levels of DDT and hexachlorocyclohexane in burbot (Lota lota l.) from Russian Arctic rivers.

The concentrations of organochlorine pesticides (OCPs =p,p'DDT, p,p'DDD, p,p'DDE, alpha-HCH and gamma-HCH) were measured in the sediments, water and burbot (whole liver and liver lipids) of eight Russian Arctic rivers near their outflows to the Arctic Ocean between 1988 and 1994. DDT was not detected in any river sediments above the limit of quantification (LOQ) of 2.5 ng g(-1) dry wt. Concentrations of DDD and DDE were only found in three of the river sediments above the LOQ of 0.75 ng g(-1) dry wt. DDT and DDE were present in only North Dvina and Pechora river water above the LOQ of 5 ng l(-1), while DDD was not found in any river above this limit. Both alpha- and gamma-HCH were found in all river sediments except for the Kolyma River at concentrations up to 2.4 and 3.5 ng g(-1) dry wt., respectively. In river water, alpha-HCH was as high as 8.6 ng l(-1) in the Ob River and gamma-HCH as high as 7.6 ng l(-1) in the Pechora River. The concentration of both sigmaDDT and sigmaHCH decreased to LOQ levels by about 1992 in both water and sediments. sigmaDDT (up to 70 ng g(-1) wet wt.) and sigmaHCH (maximum 18 ng g(-1) wet wt.) in burbot livers followed a similar temporal trend as in water and sediments. There is a scarcity of OCP data for Russia, but from what is available, we conclude that: (1) contamination of Russian rivers and burbot by OCPs is less severe in the Arctic than at lower latitudes; (2) contamination of Russian Arctic burbot is comparable to, or lower than, similar OCP contamination measured in burbot and other fish in other countries; and (3) the OCP concentrations in Russian burbot pose a negligible health risk to either humans or wildlife.

Zinc accumulation by the slime mold Fuligo septica (L.) Wiggers in the former Soviet Union and North Korea.

Samples of the slime mold Fuligo septica (L.) Wiggers were collected from an ecologically diverse selection of sites across the former USSR and in North Korea to determine their Zn concentrations. Plasmodia were collected from trees, rocks, soils, the walls of buildings and a variety of other materials and structures from 1990 to 1996. The biomass collected ranged from 305 to 968 mg, whereas Zn concentrations in plasmodia of F. septica ranged from 8400 to 23,000 mg kg(-1) dry wt. (mean and standard error = 14,200 +/- 860 mg kg(-1) dry wt.). No clear trend as to which areas produced F. septica with the highest Zn concentrations was discernable. Nor was it possible to identify any particular substrate on which F. septica grew that produced noticeably high Zn concentrations. For example, forest litter on which F. septica was found had Zn concentrations of only 25 to 130 mg kg(-1) dry wt. Our data confirm the only other study showing hyperaccumulation of Zn in F. septica, which was carried out in Finland. This ability seems to be unique to this species, but how or why it does this, or why such high Zn concentrations are not toxic to F. septica, are questions requiring future research.